Manufacture of beet sugar



Oct. 8, 1940.y G. E. STEVENS MANUFACTURE OF BEET SUGAR 3 Sheets-SheetlJ.

Filed July l2, 1938 wad lNvENToR GEORGE E. STEVENS ATTORNEYS OC- 8,1940- G. E. sTEvr-:Ns

I MANUFACTUE OF BEET SUGAR 3 Sheets-Sheet 2 Filed July 12, 1938 WWK NWSlNVENTOR 5 w N M5 E.. n mfm 5 to E m e ,G

0ct. 8, 1940. G. E. STEVENS MANUFAGTURE oF BEET SUGAR s sheets-sheet 5Filed July l2, 1938 ZOuSwl mts ON INVENTOR s. m Ms, V s am E. m E A GPatented Get. 1940 UNITED' STATES 2,217,603 MANUFACTURE oF BEET SUGARGeorge E. Stevens, Denver, Colo., assignor to The Western States MachineCompany, New York, N. Y., a corporation of Utah Application July 12,1938, Serial No. 218,727

10 Claims.

This invention relates to a new and improved process for the manufactureof sugar and, more particularly, to a process for the production ofsubstantially pure crystals, or white sugar, and

final molasses of low purity from the concentrated and partiallypurified syrup, or thick juice, obtained from the beet end operationsand evaporators in conventional beet sugar manufacture.

Any process of sugar making is a process of j eliminating non-sugarsfrom a relatively impure starting material. The easier and more quicklythe impurities can be segregated and removed from the stream of materialbeing processed, the more eicient are rening operations. Threeinterrelated and variable factors enter into the emciency of anyparticular process: the quality of the crystallized product, the purityof the end material discarded from process, and the effort expended inextracting the product and reducing the starting material to an endmaterial that can be disposed of without undue loss of sugar values.malning in the end material, or nal molasses, makes it necessary toselect an end point of as low purity as practicable. The more direct theroute to this point, the more savings are realized in intermediate stepsand the less loss or sugar values in processing and ltering steps andthrough chemical changes during such steps.

The process now used to the greatest extent in beet sugar manufactureinvolves three boilings, or three stages of operation on massecuites ofsuccessively decreasing purites. The high purity, or'white, boilings aremade principally from sugar, with added wash syrup vfrom the whitemassecuite purgings which is of lower purity than either the thick juiceor the melted sugar. The intermediate, or high raw, boilings are madefrom green syrup produced at the white stage, to which la small amountof machine syrup is sometimes added from raw pan storage to top olli thestrike; and the low purity, 0r low raw,

boilings, after grainlng on green syrup from the purity 0f about 58 to60.

In practice, the low value of sugar reevaporator thick juice and.meltedintermediate Y -white massecuite purgings, are completed with' The motorliquorV purged from the raw` (Cl. 12T-62) In the conventional practiceabout lli-15% of thevnon-sugars present in the starting material arecontinually introduced back into the head of the process with the meltedraw sugar, so that the Work of segregating these non-sugars must be`repeated and relatively large volumesof massecuite must be boiled inorder to obtain a given yield and quality of product. Moreover, thequality of the product obtainable from the white pan boilings isdenitely limited. If the purity of the-*White massecuite is made toexceed about y 92 .in an elort to raise the 'quality of the White sugar,fthe intermediate and raw massecuites become correspondingly higher thanusual in purity, and the nal molasses purged from the raw 15 massecuitecontains so much sugar that net yields y are reduced to a pointrendering ,the process less economical.

Itis common practice to pass the wash syrup from the white massecuitepurgings, because of 20 its lower purity than the thick juice and meltedintermediate sugar, through a separate blow-up tank, heater and lterbefore introducing it into the white pan boilings. In order to keep' thewhite sugar purity at a suitable point the white massecuite is grainedand boiled to fairly high crystallization before the Wash syrup isadded, but this changes the super-saturation of the massecuite, throwsthe temperatures and conditions of boiling out of adjustment, withresulting adverse eifects on uniformity of. grain size, and decreasesthe yield of white sugar per white massecuite boiling. Furthermore, thepractice of graining crystallizer massecuite on green syrup from thewhite massecuite purgings, which is often used to the extent of 20 to25% of the low raw pan contents, has a tendency to raise the purity ofthe crystallizer massecuite above the point necessary to produce nalmolasses of minimum purity. Also, the addition of machine syrup tothegrained pan at this stage of the process tends to produce uneven orsmear grain, which interferes with proper crystallization and purgingoperations.

' The only way heretofore available to attain purlties higher than 92 atthe white stage Witl.- 45 out excessive loss of sugar in the `finalkmolasses is to adopt a four-massecuite system comprising high-purityand low-purity intermediate boilings-a high high raw and a low high raw.massecuite-the sugar from the high purity intermediate boiling beingremelted and used as. the footing for white massecuite. Such a systemmakesV itnecessary to boil and purge a much greater volume of massecuitefor a given output. of white sugar, the volume of intermediatemassecuite being more than doubled. This system has been tried recentlyin a beet sugar factory where it resulted in higher costs of operation,

which olf-set the sole advantage of a white product of higher quality.

An object of this invention is to provide a new and improved process forthe manufacture of sugar which gives the optimum yield and quality ofproduct combined with the minimum of expense and effort in producing theproduct and segregating non-sugars into a low purity end material.

Another .object is to provide an optimum three-massecuite process forthe manufacture of sugar from beets characterized by the maximumexclusion of non-sugars from the white side, with consequent recovery ofwhite sugar of higher than ordinary quality, and the production of anend material, or final molasses, of desirably low purity, the purity ofthe intermediate massecuite being controlled so as to provide the mostefficient plant performance and prevent undesirable increases in rawside purity.

Another object `of the invention is to provide a process for producingbeet sugar from evaporator thick juice in which all run-offs fromcentrifugals at stages where the sugar is washed in the centrifugals arecontinually fractionated into higherand lower-purity fractions ofcontrolled purities, and in which such fractions and intermediate andraw sugars are constantly distributed so as to maintain constant controlover the purity of the massecuites and more quickly and simply toconcentrate and segregate non-sugars from process than theretofore.

Another object is to adapt such a process for the best over-allefficiency under various conditions of operation, as when the thickjuice is of normal purity and when it is abnormally low in purity.

Still another object of the invention is to pro-I vide a process formaking beet sugar in which the white pan boilings are continuallysupplied with melted raw sugar of considerably higher purity than thenormal White massecuite purity, while the crystallizer massecuite andthe final molasses produced therefrom remain at no greater than theirusual low purities.

A further object is to provide la three-massecuite process for themanufacture of beet sugar in which each massecuite is boiled from asingle standard liquor of controlled purity, the liquor for whitemassecuite being continually produced as a composite of incoming thickjuice and process materials of controlled purities and the liquors forintermediate and crystallizer massecuites being continually ,produced ascomposites of other proc-f ess materials of controlled purities.

Among other objects of the invention are to eliminate the usual separatetreatment and boiling-in of wash syrup from white massecuite purgings,and to eliminate the graining of crystallizer massecuite on green syrupfrom White massecuite purgings, together with the disadvantages whichattend such practices.

Heretofore each stage of the sugar process has generally been consideredas a unit process from which to obtain crystals and relatively impurerun-offs, and the purities of the several massecutes have been acceptedas dictated by the character of the varying materials normally producedby these several unit processes and by the necessity of producing a low'purity final molasses. I have departed from this concept and have foundthat all benefits heretofore obtainable from the perfection of boilingand purging operations at each stage may be realized, and that theefliciency of the Whole process in respect of product quality and costsof manufacture may be greatly improved, by regulating the character ofthe materials produced at each stage and distributing them in theprocess so that the purities of the several boilings are keptunderconstant control and adjusted for the best performance of theirindividual and collective functions.

The preferred embodiment of my invention in the manufacture of beetsugar is an improved three-massecuite process including a high purity,or White, stage which yields the marketable product-white sugar-anintermediate stage, and a low purity, or raw, stage which produces theend material-final molasses. 'Ihe purity of the White massecuite israised above normal by boiling it from the thick juice entering theprocess, to which has been added a large amount of melted sugar, ofconsiderably greater purity than the White massecuite, and a .high whiterun-olf fraction from the white centrifugals, of controlled puritysubstantially as great or greater than the White massecuite. A sharpseparation is made between centrifugal run-offs in the purging of thewhite massecuite so as to produce controlled purity low white and highwhite runol fractions. lThe low white fraction is used as the principalmaterial for the intermediate stage of the process. The intermediatemassecuite is regulated and kept at an abnormally low purity in relationto the purity of the white massecuite and at the point best suited forthe production of a low-purity material for the crystallizer massecuiteboilings by fractionating the run-offs obtained in purging theintermediate massecuite into controlled high intermediate andlow-intermediate fractions and returning the higher purity fraction tothe intermediate pan storage tank for combination with the low whitefraction. The "low-intermediate fraction represen-ts the optimumavailable drop from the controlled intermediate massecuite purity and.is passed to the raw pan for the production of crystallizer massecuiteof desirably low purity..

The treatment of the crystallizer massecuite is carried out underuniform and accurate control so as to yield raw sugar of extraordinarilyhigh purity and separate centrifugal run-off fractions,

one a high raw fraction of about the same purity as the low intermediatefraction, which is combined with the-latter to form the liquor forcrystallizer massecuite boilings, and another a final molasses ofoptimum low purity.

In the preferred practice, when the beets are ot abnormally low inpurity, this high purity raw sugar, as well as the intermediate sugar,is melted (dissolved) and passed directly to the blow-ups where it iscombined with incoming thick juice. The purity of the white massecuiteand, consequently, the quality of the white sugar are raised aboveconventional standards by this practice. Furthermore, the reintroductionof large amounts of non-sugars into the process is avoided, the amountof white massecuite to boil for a given production of white sugar ismaterially reduced, and the total amount of all massecuites to be boiledper unit output of white sugar is reduced, which mean a more directroute to the desired product, lower costs of manufacture, and less lossof sugar through process losses and chemical changes. The sending ofmelted raw sugarv through carbonation and other treatments prior tointroduction into .thehead of the process is eliminated except underextraordinary circumstances. v

In the accompanying drawings Figure 1 is an illustrative iiow chartindicating the preferred manner of applying my invention to themanufacture of beet sugar. Figure 2 is an illustrative iiow chart ofanother embodiment of the process, and Figure 3 illustrates 'a thirdembodiment of the process. The indications of units of equipment onthese drawings are merely diagrammatic. units of each piece of equipmentmay be used, depending upon :the nature and capacity of the equipmentand the character and volume of plant operations, and also that otherequipment and operations which have no material bearing on the presentinvention may be present in any system for practicing the process. l

The high purity, intermediate and low purity boilings take place invacuum pans designated on the drawings by the characters A, B and C, re-

spectively. The vacuum pans are supplied with footings from storagetanks A1, B1, C1, respectively. Y'Ihe A and B pans discharge theirstrikes into mixers A2 and B2. The C pan discharges into crystallizerapparatus C2,`in which the crystallizer massecui-te is cooled to promotethe growth of crystals and the exhaustion of sucrose from the molasses,and from this the crystallized of construction. It is important,however, that the mixers be equipped to permit accurate control over theconsistency of the massecuite and toA @keep uniform the temperature andfluidity of successive charges as withdrawn for treatment in thecentrifugals, which may best be accomplished, with maximum capacity andminimum dissolution of sugar grain, by use`of the processes andapparatus described in my United States patents, Reissue No. 20,556 andNo. 2,086,951, respectively. It also is important to best performanceAthat the centrifugals at each stage be capable of substantially uniformoperation and of eicient elimination of syrups, that they be equippedwith means for eecting a sharp separation between syrups owing fromthecurb walls at different time inl tervals, and that the purging, Washingand syrupseparating operations of each centrifugal cycle be kept underaccurate and timed control and adapted for controlled variation to-suitrequirements when the qualities of the massecuite undergoing treatmentare subject to change. Each centrifuging cycle on a given massecuiteshould involve a uniform period during which the sugar crystals arepurged of substantially all of the mother liquor that can be eliminatedefficiently by centrifugal force, a uniform time and period for applyingcontrolled amounts-of wash water after such purging, and a uniform timefor actuating the syrup separating means. Centrifugal apparatus andprocesses possessing these features have been developed by EugeneRoberts and described in hisissued patents and pending applications, andare now well known in the American sugar industry.

It will be understood that one or more The sucrose-bearing starting orraw material A for the process consists of evaporator thick juice,

or, in a Steffens factory, evaporator thick juice bonation'as inconventionalpractice; hence its purity is somewhat higher than in thepractice of the usual beet sugar process. 'I'his material is passedthrough the blow-ups or receiving tank and thence through heaters andfiltration apparatus to the storage tank A1. In addition, melted sugarand a high white run-off` fraction consisting essentially of wash syrupfrom the white centrifugals, both of considerably greater purity thanthe thick juice, are continually supplied to the tank Al-preferablyafter using the high white fraction, with added hot water, to dissolvethe washed intermediate and raw sugars in the high melter, passing thematerials together to the same blow-ups, and owing them through the sameheaters and filtration equipment. The regular addition to the thickjuice of large amounts of these materials of greater purity, from whichall but a small proportionof non-'sugars has been eliminated, provides asingle standard liquor for white massecuite boilings, results in asubstantial increase in the purity of thewhite massecuite and .permits asubstantial improvement in the quality of the white sugar recovered fromthe White stage operations.

The boilingsl at A are carried out in the known manner for Whitemassecuite, and the massecuite is dropped from A into mixer A2 fromwhich charges of substantially uniform and controlled uidity arewithdrawn successively for treatment in the white sugar centrifugals A4.The centrifugal operations are preferably kept uniform and under carefulcontrol and are of such nature as to effect rapid elimination of motherliquor, or green syrup, from the sugar grain. The green syrup iiowingfrom the curb of each centrifugal is collected in a trough A5 as theprincipal constituent of the low white run-olf fraction.. 'I'he Asugarremaining in the centrifugals after a predetermined period for expellingmore than 90% of the green syrup is freed of the residual adheringmother liquor and impurities by the application of a clear liquidwashing agent, such as Water. At a predetermined interval after applyingAthe wash water the syrup separator is tripped to divert liquid owingfrom the curb into a trough A6, so that wash syrup of predetermined andrelatively high purity (substantially as high or higher than the whitemassecuite) is sharply separated fromthe preceding syrup and collected sparately as the high white fraction for recirc ation to white panstorage at A1. In this manner three materials of distinct and controlledpurities are produced from the White massecuitewhite sugar of unusuallyhigh quality and two separate high white and low white" run-olffractions, the ist consisting essentially of Wash syrup and the secondconsisting essentially of green syrup with a very small predeterminedamount of -wash syrup. n

The low white fraction contains a large percentage of recoverablesucrose. With the white produce a crystallizer massecuite of optimum lowpurity. According to my process, I maintain control over the purity ofthe intermediate massecuite and cause the mother liquor of theintermediate massecuite to stay at a purity best suited for thecrystallizer massecuite boilings by continually combining the low whitefraction with an intermediate run-off fraction of controlled .purity soas to keep a standard liquor for intermediate boilings in theintermediate storage tank B1.

Boilings are carried out at B on liquor from the storage tank B1, andintermediate massecuite is dropped into the mixer B2 and thence intocentrifugals B4 for purging. Again, the uidity oi successive chargesintroduced into the centrifugals should be kept uniform and undercareful control, and purging, washing and syrup separating operations atthe intermediate centrifugals should be maintained under predeterminedtimed control.

Instead of effecting the syrup separation at the intermediate stage toproduce a. run-o' fraction of very high purity, as preferably done atthe white stage, a sharp separation between runoifs is eected to producea low intermediate fraction, consisting of green syrup only, and a highintermediate Afraction containing regulated proportions of green syrupand wash syrup. The proportion of green syrup depends upon the purityired for the crystallizer massecuite and the purity and volume of thelow white fraction. In a. Steffens factory the raw massecuite purity maybe somewhat higher than in a non-Steffens factory without substantialeconomic effect on the process. With substantially uniform and eiiicientcentrifugal operations, the purity of the high intermediate fraction isreadily controlled by xing the moment of actuation of the syrupseparator in each centrifuging cycle so that after such actuation asubstantially definite amount of green syrup ows into the trough B6, tobe followed by the wash syrup after the wash water is applied. This highintermediate fraction isl combined with the low white fraction at B1 toprovide liquor of controlled purity for intermediate massecuiteboilings` while the low intermediate fraction is passed to raw panstorage C1 for boiling into raw, or crystallizer, massecuite at C.

The sugar produced at the intermediate stage ordinarily attains a purityof 98 to 99. It is passed to the high melter where it is dissolved inthe high white fraction .and added hot water, as mentioned above, andfrom the high melter it passes to the blow-ups for combination with theincoming thick juice.

At the raw stage of my process the pan liquor consists principally ofthe low intermediate runoff fraction. Under normal conditions ofoperation, as illustrated in Figure: 1 ofthe drawings this is combinedwith a "high raw run-off fraction, of about equal purity, produced atthe raw centrifugals. The crystallizer massecuite boiled at C is droppedinto crystallizer apparatus C2 where it is cooled. to promote additionalcrystallization of its Asucrose content. From C2 it is passed to a mixerC:l overlying the raw centrifugals C4. From the mixer, after treatmenttherein to increase their fluidity and render their consistency uniform,successive charges of the massecuite are introduced into thecentrifugals. The purging of the uniformly conditioned charges ofcrystallizer massecuite is preferably carried out so as to attain a rawsugar purity much greater than heretofore obtained -in known processes,

while avoiding any appreciable increase in final molasses purity. Eachcentrifugal is operated to effectmaximum elimination of the green syrupwithin a substantially denite time interval. After such a time interval,the sugar remaining in the centrifugal is washed with a predeterminedsmall volume of wash water. The centrifugal operations are preferablycontrolled so that the flow of mother liquor into the green syrup troughC5 is terminated at approximately the instant when the wash syrup isready to enter this trough, and the wash syrup is then collectedseparately in a separate trough C6 as the high raw fraction which istaken to the storage tank C1. With uniform heat conditioning of the rawmassecuite before centrifuging according to the process of my U. S.Patent Reissue No. .20,556, and with eflicient and uniform centrifugaloperations and accurate syrup separation, I have found it possible innormal operations to wash the raw sugar in the centrifugals to a purityof 97 to 99 while separating the wash syrup sharply from the motherliquor and producing final molasses of as low or lower purity thanobtainable in the usual process where no washing is 'employed. Shouldthe purity of the low intermediate fraction entering the raw stage,under special circumstances, be too high for proper raw stageoperations, a predetermined proportion of green syrup may be collectedwith the wash syrup in the trough C6 and returned to tank C1, thuskeeping Ithe raw massecuite purity at the proper point and preventingany undesirable increase in iinal molasses purity.

The raw sugar of 97 to 99' purity obtained from the low purity stage ofoperations contains relatively little of non-sugars. The major portionof the non-sugars have been segregated and diverted from the process inthe final molasses. Most of the residual non-sugars which normally wouldbe present in the raw sugar have been removed in the high raw fraction,which is of about the same purity as the raw massecuite and is returnedto the raw pan with the low intermediate fraction for extraction of itssugar. The washed raw sugar is passed directly to the high melter, whereit is dissolved in the same manner as the intermediate sugar, and fromthe high melter it is passed as part of a sugar solution of relativelyhigh purity to the blow-ups for combination with incoming thick juiceand reentrance into the head of the process.

The process substantially as described above provides the bestcombination of high product quality, low iinal molasses purity and lowcosts of operation in beet sugar making when the nonlsugar content, suchas sulfates and gums, in the thick juice is not abnormally high. Whenpoor quality beets keep the white massecuite purity much below normaland when the raw massecuite is boiled or crystallized improperly or forany other reason is ofa quality preventing eiective Washing to highpurity, the raw sugar is preferably discharged from the centrifugals atC4 without washing, and this unwashed raw sugar of low purity (about88-92) is preferably dissolved in the low melter, in a portion of thelow white fraction diluted with hot water, and then taken tointermediate storage, as indicated by the flow chart in Figure 2 of thedrawings. In this wayv of white massecuite purity and volume of boil-Jmgs. When operations at the raw stage are carried out such that thepurity of the washed raw sugarl remains considerably below normal, forexample, below about 96 yet much higher than the intermediate massecuitepurity, or when the washed raw sugar is of abnormally high sulfatecontent; it may be preferable to modify the distribution of the rawsugar in the process, as indicated by the ow-chart in Figure 3 of thedrawings, passing it to the low melteir, where it is dissolved in hotwater or hot sweet water, and then to rst or second carbonation forpartial purication and subsequent reintrodution into the head of theprocess.

My process, as normally practiced, provides y an optimumthree-massecuite system for making beet sugar. It involves the formationof three standard liquors for pan boilings, each of which is aredetermined composite of materials' of controlled purity. The whitemassecuite, at-the head of the process, is constantly maintained at avery high purity and produces white sugar of extraordinarily highquality. 'Ihe crystallizer massecuite, at the nal stage of lthelprocess, produces an end materialcharacterizedfby optimum exhaustion ofsucrose. Between these two lies an. intermediate massecuite, the purityof which is controlled by fractionation and distribution of run-ois sothat increases in the purity of the raw massecuite which otherwise wouldresult from the high white massecuite purity are avoided. The optimumsegregation of sugars and non-sugars consistent with this type ofoperation is eiected at each stage, and the distribution of materials iscarried out so that the directness and economy of the route from start-"ing material to white sugar of high quality are greatly improved.

'Ihe significance of my process may be gathered in part from thefollowing tabulation of data representing, on the one hand, averageresults of beet sugar processes which follow the general .three-boilingpractice mentioned hereinabove, and on the other hand, approximateresults which may be obtained by the full use of the present invention.These data. are based upon the processing of thick juice of the samequality. They are presented only by way of illustration, since thespecic gures will vary in practice, depending upon the quality of beets,operating conditions, operating supervision, etc.

WHITE Sfraer;

- Prior predice New predice I .White massecuite ccmpo- I Whitemassecuite components. nents.

A. Thick juice and melted A single liquor, supplied sugar fromyblow-nps, continually from blowheaters and filters, ups, heaters andfilters, 90-92 purity, consisting consisting of of: Percent (1)Evaporator thick (l) Eveporator thick juice, 92 purity, jnice.92purity.6plus melted raw (2) Liquoriromhigh sugar from low melter, 97 pumelter,at 87-90 ri 34 purity, added at including: 1st or.2nd carbo- (a)Intermediate n ation, 89-91 pusugar, 99 rit-y. purity 16 (2) Meltedintermediate (b) Raw sugar,

sugar, irom high puri 8 n ielter, 94-96 pn- (c) High white mty. lfraction, 94 B. Wash syrup from white purity l0 purgings, after treatf fment in special blow- 34 ups, heaters and l- White massecuite from aboveters, 87-89 purity. liquor, 94 purity. White mesecuite=Al-B, 89-

91pnnty.

A. Green syrup from white p ngs,82-85 purity. B. Mach e syrup fromlowraw panl storage,

7l-74 purity.

Intermediate massecuite=l00% 4 A, 82-85 purity or (occasionally), A+B,81;-84 purity.

" single-liquor from intermediate pan storage, consisting of:

Percent (l) Low white fraction, 87 purity. 70 (2) High intermedi-A atefraction. 78 purity 30 Intermediate massecuite from above liquor, S4purity.

FINAL STAGE Prior practice New practice IIL Crystallizer massecuite III. Crystallizer massecuite components components. A. Green syrup fromwhite A single liquor from low purgings, to grain pan, raw pan storage,consist- H82-85 p ing oi: B. Machine syrup from l Percent intermediatepurg- (l) Low interings, 71-74 purity. m e d i a t e Crystallizermassecuxte=A+B, fraction, 74

72-75 purity. Funtym... 90 IV. Final molasses purity 58-60. (2) H gliraw fracl tion, 74 purity... l0 Crystellizer massecuite from aboveliquor, 74 purity. IV. Final molasses purity 58.

The invention is not restrictedq to the details of embodimentsdescribed-hereinabove for purposes of illustration, but extends to otherpractical embodiments utilizing its novel features as set forth in theappended claims.

`I claim: I

Y.1.'In theprocessing of white beet sugar andl nal molasses fromevaporator thick juice by a succession of massecuite-boiling andcentrifuging operations in three stages at successively lower purities,the steps which comprise washing the sugar in centrifugals at each stageto purlties greater than the highest massecuite purity, separatingcentrifugaly run-offs at each stage into higher-purity and lower-purityfractions of predetermined controlled purities, returning the higherpurity fractions for boiling into massecuitesat the respective stages,withdrawing the lower purity fraction at the lowest stage from processas fmal molasses, passing the lower purity fractions from the otherstages to the stages next below for boiling into massecuite, melting thewashed sugar from the intermediate stage and passing the same to thehighest purity stage for boiling into white massecuite, melting thewashedsugar from the lowest stage and passing Vthe same to a higherpurity stage for boiling into` massecuite, and withdrawing the washedsugar from the highest purity stage from process as the white beet sugarproduct.

2. In the processing of white beet sugar and final molasses fromevaporator ythick juice by a succession of massecuite-boiling andcentrifuging operations in three stages at successively lower purities,the steps which comprise purging and Washing the sugar in thecentrifugals at the lowest, or raw, stage to a purity above the Whitemassecuite purity, separating raw censuccession of massecuite-boilingand centrifuging operations in three stages at successively lowpurities, the steps which comprise xing the purity of the lowestmassecuite for the production of mother liquor of optimum low purity tobe removed from the process as nal molasses, keeping the highestmassecuite at the optimum purity for the' production of high-qualitywhite sugar, washing the highest sugar and separating centrifugalrun-offs into a high white fraction consisting substantially entirely ofwash syrup of a purity at least as high as the white massecuite and alow white fraction consisting essentially of green syrup, washingthesugar at the intermediate stage and separating centrifugal run-offs intoa high intermediate fraction and a low intermediate fraction consistingsubstantially entirely of green syrup, combining said high intermediatefraction with said low white fraction and boiling massecuite at saidintermediate stage therefrom, controlling the purity of the highintermediate fraction in relation to the purity of the low whitefraction to keep said intermediate massecuite at normal purity inrelation to said lowest massecuite, boiling said low intermediatefraction into said lowest massecuite, melting the washed sugar from theintermediate stage and passing the same to the highest stage for boilinginto white massecuite and melting the sugar produced from the lowestmassecuite and passing the same to a higher purity stage for boilinginto massecuite.

4. In the processing of white beet sugar and final molasses fromevaporator thick juice by a succession of massecuite-boiling andcentrifuging operations in three stages at `successively lower purities,the steps which comprise washing the sugar in centrifugals at each stageto purities greater 4than the highest massecuite purity, separatingcentrifugal run-offs at each stage into higher-purity and lower-purityfractions of predetermined controlled purities, returning the higherpurity fractions for boi-ling into massecuites at the respective stages,withdrawing the lower purity fraction at the lowest stage from processas final molasses, passing the lower purity fractions from the otherstages to the stages next below for boiling into massecuite, dissolvingwashed sugar from all but the highest stage, introducing the dissolvedwashed sugar into the highest stage for boiling into massecuite with thehigher purity fraction from said stage and with incoming thick juice,and withdrawing the washed sugar at the highest stage from process aswhite sugar of high quality.

5.'In the processing of white beet sugar and nal molasses fromevaporator thick juice by a succession of massecuite-boiling andcentrifuging operations in three stages. at successively lower purities,the steps which comprise purging and .washing the sugar in thecentrifugals at the lowest, or raw, stage to a purity of at least 96,separating raw centrifugal run-ois into a higher purity fraction of a,purity near the raw massecuite purity, consisting essentially of washsyrup, and a lower purity fraction consisting substantially entirely ofgreensyrup, withdrawing the lower purity" fraction from process as nalmolasses of optimum low purity, dissolving said washed raw sugar,passing the dissolved raw sugar to the highest stage for boilingdirectly into white massecuite, and returning said higher purityfraction for boiling in to further strikesA of raw massecuite.

6. A three-massecuite process for producing white beet sugar and nalmolasses from evaporator thck juice, which comprises fixing the purityof the raw, or crystallizer, massecuite for the production of finalmolasses of optimum low purity, boiling the white massecuite fromincoming thick juice and continually added process materials ofconsiderably greater purity than the thick juice including a controlledrun-off fraction from the white purgings and dissolved washed sugar,maintaining the intermediate massecuite at a normal purity in relationto the xed purity of the raw massecuite .and at an abnormally low purityin relation to the purity of the white massecuite by including therein arunoff fraction of predetermined purity and volume from the intermediatepurgings, boiling said raw massecuite principally from a run-offfraction consisting of green syrup from the intermediate purgings,melting the sugar from said interme 'diate massecuite and recirculatingthe same forboiling into white massecuite and melting the sugar fromsaid raw massecuite and recirculating the same for boiling intomassecuite of higher purity than said raw massecuite.

'7. A three-massecuite process for producing white beet sugar and finalmolasses from evaporator thick juice which lcomprises fixing the purityof the raw, or crystallizer, massecuite for the production of nalmolasses of optimum low purity, washing the sugar from each massecuitein centrlfugals, boiling the white massecuite from the incoming thickjuice and added process materials of considerably greater purity thanthe thick juice including a run-off fraction consisting substantiallyentirely of wash syrup from the white purgings and dissolved washedsugar, maintaining the intermediate massecuite at a normal purity inrelation to the xed purity of the raw massecuite and at an abnormallylow purity in relation to the purity of the white massecuite by boilingthe same from a run-off fraction consisting essentially of green syrupfrom the white purgings and a run-oi fraction from the intermediatepurgings consisting of predetermined proportions of green and washsyrups, boiling said raw massecuite from a run-01T fraction consistingof green syrup from the intermediate purgings and a run-oi fractionconsisting essentially of the wash syrup from the raw purgings andvdissolving washed intermediate and raw sugars and adding them toincoming thick juice as aforesaid.

8. A three-massecuite process for producing white beet sugar and finalmolasses from evaporator thick juice which comprises fixing the purityof the raw massecuite for the production of mother liquor of optimum lowpurity to be removed from the process as the iinal molasses,.

washing the sugar from each massecuite in cen'- trifugals to a puritygreater than the white massecuite purity, separating centrifugal runoisfrom each massecuite into higher-purity and lower-purity fractions ofpredetermined controlled purities, returning the higher-purity fractionsfor boiling into massecuites at the respective stages, combining thelower-purity white and intermediate fractions, respectively, with thehigher-purity intermediate and raw fractions and boiling intermediateand raw massecuites from the respective combined materials, withdrawingthe lower-purity raw fraction from process as the nal molasses,dissolving washed intermediate' and raw sugars, combining said washedsugars with the higher-purity white fraction and with incoming thickjuice and boiling the White massepurity in relation to the fixed purityof the raw massecuite and atan abnormally lowpurity in relation to thewhite massecuite.

, 9. A three-massecuite process for producing` white beet sugar andfinal molasses from evaporator thick juice which comprises xing thepurity of the raw, or crystallizer massecuite for the production of nalmolasses of optimum low purity, boiling the white massecuite from theincoming thick juice and added process materials of considerably greaterpurity than the thick juice including a run-0E fraction consistingsubstantially entirelyk of wash syrup from the white purgings anddissolved washed sugar, boiling said raw massecuite from a run-0Efraction consisting of green syrup from the intermediate purgings.purging said raw massecuite to produce the nal molasses and unwashed rawsugar, dissolving the raw sugar, maintaining the intermediate massecuiteat a normal purity in relation to the xed purity of the raw massecuiteand at an abnormally low purity in relation to the purity of the whitemassecuite by boiling the same from dissolved raw sugar together with anin-oi!- fraction consisting essentially of. green syrup from the whitepurgings and a run-oi'fraction from the vintermediate purgingsconsisting of'predetermined proportions of green and wash Syrups, anddissolving washed intermediate sugar and adding it to incoming thickjuice as aforesaid.

10. In a three-massecuite process for the production of white beet sugarand final molasses from evaporator thick Juice, the steps which compriseboiling the white massecuite only from thick Juice and process materialsof greater purity than the thick juice and thus maintaining the whitemassecuite at a purity of at least 92, boil-,- ing the intermediatemassecuite from process materials including green syrup from the whitemassecuite purgings and a special run-o of controlled purity from theintermediate massecuite purgings, producing said special run-o bycombining wash syrup and green syrup from the intermediate purgings inproportions regulated to maintain the intermediate massecuite at anabnormally low purity in relation to the white massecuite purity and ata normal piu'ity in relation to the lowest purity, or raw, massecuite,and passing the remainder of the green syrup from the intermediatepurgings to the lowest purity stage for boiling into raw massecuite.

GEORGE E. STEVENS.

